Gas or oil internal-combustion engine.



puo. mmm.V Patented 1an. I4, i902.

E. THOMSON. I GAS 0R OIL INTERNAL COMBUSTIN ENGINE.

' (gppunation suenan. 17, 189e.) (No Model.) 3 Sheets-Sheet l.

`Patented Jan. I4, |902.

E. THMSUN. GAS 0R UIL INTERNAL COMBUSTION ENGINE.

(Application filed Jan. 17, 1898.)

3 Sheets-Shet 2.

(No Model.)

E www www N EEES..

No, 69|,o|7. Patented 1an. i4, |902. E. THoMsoN.

GAS 0H UIL INTERNAL CMBUSTIIUN ENGINE.

(Application led Jan. 17, 1898.) (No Model.) 3 Sheetsr-Sheet 3.

turion.

EIiIl-IU THOMSON, `OF SVVAMPSCOTT, MASSACHUSETTS.

GAS OR OIL INTERNAL-COVIBUSTION ENGINE.

SPEGIFICATILON forming part of Letters Patent No. 691,017, dated January14, 19032. Application filed January 17., 1898. Serin-l No. 666|901. (Nomodel.)

To @ZZ whom, t may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States,residing in the town of Swampscott, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Gas orOil Internal- Oombustion Engines, of which the following is aspecification.

The objects of the invention are to secure greater manageability andeconomy of working, to prevent as far as possible bad effects ofpreignition in large engines, and to secure when desired in a simplestructure effects of large expansion from a small fuel charge and alsoto secure a complete combustion of such charge in excess of air.

In my invention I take in in one cylinder a charge of air, while at thesame time drawing in or filling in another cylinder in freecommunication with the first with a combustible mixture of eitherinflammable gas or air in proper proportions for explosion when ignitedor a mixture of oil or gasolene vapor with air for the' saine purpose.The two charges in adjoining and connected cylinders then undergocompression by the return stroke, and at the conclusion of suchcompression the fuel or combustible charge is fired either by its owninternal heat or the heat of the surrounding parts of the cylinder inwhich it is placed or by a suitable electrical or other ignition device,such as a hot tube. The charge thus tired at or near the completion ofthe compression-stroke begins its burning in the cylinder in which ithas been compressed, andthe great expansion during its burning forces itoverlin large part through the compressed air in the other cylinder,with which it mixes and thoroughly burns. This produces a rise ofpressure in both cylinders almost simultaneously, after which thepower-stroke is made by the gases expanding and forcing' the pistonsforward to the end of their play. W'hen this has occurred, theexhaust-valve is opened and the gases escape from both cylinders on thefourth stroke or the second return stroke.

Other features of my invention will be pointed out in connection withthe accompanying drawings.

Referring to the drawings, Figure 1 is an elevation in part section ofan engine embodying my invention. Fig. 2 is a partial end elevationcorresponding to Fig. 1. Figs. Sand 4 are details of one of the threeways by which the valves may be operated, though this is of no specialconsequence, provided they are given their proper sequence of openingand closing. Fig. 5 is an end elevation of the engine shown in Fig. 1.Fig. 6 is a plan view of the valve-moving parts of Fig. 1. Fig. 7 is adiagram indicating the relation of the two cylinders. Figs. 8, 9, 10,and lll show diagrammatically the cycles of operation. Figs. 12 and 13are approximate diagrams resemblingindicated diagrams. Figs. 1e and 15show variations in the cycle. Figs. 16 and 17 are diagrams of thevariation. Fig. 18 shows the relations of cranks of the two cylindersunder certain conditions.

In Fig. 1, B B represent the bed-plate ofthe structure, upon whichthejournalsJ Jgare carried for the support of the revolving shaft, uponwhich the fly-wheel or power-pulley W is mounted, as shown. A set ofcranks are constructed and mounted so as to have their angular relationor sequence of operation changed as desired, so that they may be putinto coincidence or kept in phase, so to speak, or thrown ont of phasein a certain sequence to he explained. This feature, however, can beomitted and the cranks given a definite relation by originalconstruction, so that they are either coincident or somewhat displacedin relation to each other. change of relation indicated in the figuremay be accomplished in any desired way, as that is not an essentialfeature of my invention. As illustrative of the change of lrelation thedisk A may have a slot of some angular extent through which a strongbolt is passed. to the adjoining disk C,and when they are drawn firmlytogether around a central pin P they remain in the relation so givenduring the action of the engine. A large piston P" is connected to itsappropriate crank-pin by a suitable connectingrod,as shown,and thesmaller piston P2 also connected to its own crank-pin so as to movefreely. The cylinders may be provided with water-jackets, the design orconstruction of which is not an important featureA to be described here.

I is an inlet-valve for air.

E is the exhaust-valve for gases to be ab- The IOO

stracted, while the valve G may be called the fuel-admission valve, itbeing preferred to mix with the fuel admitted with the valve G a certainproportion of air, although this is not essential where a fixed gas,like coal-gas, is used; but where oil of a fai rly high boilingpoint isadmitted it is preferable to secure an admixture of air, which tends tokeep it from condensing. In the use of oil a chamber V, heated by a lampL, may be employed for vaporizing the oil injected therein by asupplypump'S, and an opening a for admission of air may be made in V, soas to miX the incoming charge as desired. With gas as a fuel thesupply-pump S can be supplanted by a gaspump or a simple connection tothe gas-sup ply under a small head.

A suitable gearing, such as an endless chain K, drives from the mainshaft a cam-shaft K2, the'relation of rotations being two of the mainshaft to one of the cam-shaft K2, as usual in gas-engine construction.Any other suitable gearing may be used to operate the valves in aparticular sequence; but, as shown, the shaft K2 is mounted on suitablebearings and has upon it a set of cams C' C2 C3. Itmay also carry thegovernor H for disengaging the fuel-admission cam C2 or so operate uponthe valves as to render the engine incapable of performing its regularcycle. 'lhe governor H could, of course, be mounted upon thevmain shaftwith any suitable form of disengaging apparatus for the valves; but sofar as these parts are used in the figures they may be taken asillustrating the actions taking place in the operation of thel engineand not as essential constructions for performing these operations.

The valve-stems of the valves G, I, and E are suitably guided, as shown.Springs Z Z2 Z8 are provided, and by these springs the valves areclosed, while roller-bars may be provided for the cams to run on andactuate the valve during the operation.

In Fig. 3 is shown a form of disengagiug mechanism for preventing theopening of the y valve G by disengaging its operating-cam C3 cam C2.

,m f i from the shaft and allowing it to fail to rotate with cam-shaftK2 when the speed is such that the part L' under control of the governorH is drawn along on the shaft away from the The cam is so mounted as tobe free of the shaft except when propelled by the part L, having aprojection engaging with a corresponding projection on the cam C3, asshown. Cam C3 has, however, no lateral play or end playalong the shaft,being mounted lbetween suitable collars or otherwise sustained in properrelation. It is preferable also to arrange that the cam C3 shall be freeto be turned around the shaft K2 or the shaft K2 to turn within the camC3in one direction only. -To accomplish this result, the cam C3 maycarry with it a pair of pawls p p, Fig. 4, engaging with theratchet-wheel r, carried by the shaft K2. This will permit engagement ofthe cam and its disengagement by the part L and at the same time willprevent the valvestem and spring Z3 from throwing the cam forward in thedirection of the arrow, which would otherwise occur when the cam hadpassed the middle point of opening of valve G and the valve was about toclose on the receding side of the cam.

The sequence of connections of the cams C C2 C3 is as follows, and theoperation of the engine may be explained. in connection with thissequence: Assuming that thepistons of the engine are in the positionshown in the figures-t'. e., that the larger piston P is on dead-centerand the smaller piston P2 is following the same to a certain angle ofthe crank-pins-then very soon after the rotation in Fig. 2 has carriedthe crank of P/ over center the crank-pin of P2 will have driven saidpiston nearly to the bottom of the cylinder in which it moves. Theclearance-space for both pistons will then be a small space back ofpiston P2 and alarger volume of clearance back Yof piston P. Thecontinued rotation will now draw piston P downward and forward, and camC2 will be set so as to allow a charge of air to be drawn in. As soon,however, as piston P2 begins to leave the bottom of its cylinder valve Gis opened by cam C3, and the same movement lnay be made to inject adeterminate quantity of vaporizable oil by pump S into the vaporizer Vor a given volume of gas may be admitted through valve G. Amoderate-sized opening at a allows a little air to enter V, which mixeswith the indrawn charge. Vhile, therefore, the space back of piston P isbeing filled with air through the inlet-valve I the space back of P2 isbeing filled through G with combustible gas or vapor mixed with airwhich comes along therewith and with a portion of the air enteringthrough valve I when open. This indrawing action continues until thelarge pist-on P has passed outward and is slightly over its dead-center,or the admission may, if desired, be cut olf at some intermediate point.When both cylinders are filled with their appropriate gases,

piston P' begins to return and is followed by4 piston P2, according tothe chosen angle of displacement of their'cranks, and the com- IIOpression stroke in both cylinders begins. f

The piston P having slightly the lead of piston P2, the tendency is tokeep the combusti ble mixture in the space back of P2, owing to a slightflow of air from the larger cylinder into the smaller. This air notbeing mixed with combustible gases itself, except-it is driven into thesmaller cylinder, tends to prevent too early ignition of the charge inthe smaller cylinder. When the large piston P2 has reached the end ofits upward or compression stroke, the gases in both cylinders will havereached a pressure depending upon the space allowed them and theirtemperature. This may be set so as to be fifty, seventy-five, or onehundred pounds per square inch or other pressure found desirable. As thepiston P is on a dead-center, the piston P"3 in falling goes oncompressing the charge, and it is during this period or relation thatthe firing of the charge takes place by the combustible mixt-ure beingdriven when compressed into an ignition-tube L, especially on thestarting of the machine. The firing of the charge, however, occurs onlyin the space immediately adjacent to piston P2, and the burning thereof,attended by an increased pressure and volume, causes the flame from thesmaller cylinder to be shot briskly into the space back of the largepiston P iilled with compressed air; If the expulsion is made with anexcess of combustible in the charge found in P2, the excess of air in Pcompletes the combustion. This burning greatly raises the pressure backof both pistons, and as the cranks continue turning the work ofexpansion is taken upon piston P at the first, while on account ofdisplacement piston P2 still continues toward the bottom of itscylinder, tending thus to expel nearly the whole of its charge therefrominto the larger cylinder. A small amount of negative Work isaccomplished during this transference, but only when the piston P2follows the piston P through a certain angle of cranks. When piston P2passes over the dead-center, both pistons then act together for power'or delivery of return force by the cranks to the main shaft of the wheelW. This may be called the power-stroke 7 of the engine, and the cylinderin which piston P' plays may be called the power-cylinder, while thecylinder in which piston P2 plays, inasmuch as it serves as a mixing andcompressing space for the combustible charge, may be termed thefire-cylinder. On the completion of the downward or power stroke by thepistons they again return or move upward, during which stroke theexhaust-valve E is open and the waste gases are expelled, leaving onlysuch an amount thereof as fills the clearancespace back of the largepiston P and partly that back of piston P2 at the time of the completionof the exhaust-stroke, after which the operation proceeds as before, sothat the engine Works in a general way according to the Otto cycle, butin a different wayin regard to the charges of compressed gas and theirdistribution.

It is desirable that after the engine is under way the cylinder in whichpistou P2 plays shall not be kept too cold, as, in fact, the ignitionmayfinally be allowed to depend upon the heat increase in the chargeproduced in it by compression and by the communication of heat theretoin the vaporizer V or from the cylinder-walls to the cylinder for pistonP2. In such case the ignition tube and lamp L would only be required toworkat starting, the subsequent firing being due to a species ofpreignition, such as would be harmful in most types of engines, butwhich in my invention may be relied upon to actually produce firing ofthe charge. It will be understood that a water-jacket or artificialcooler' of the cylinder-walls may be provided wherever the temperatureof parts is liable to rise unduly, and in Fig. l spaces are indicatedaround valve G and around both cylinders which may be employed aswater-jackets by the i'low of a regulated supply of water therethrough.

In Fig. 5 the end elevation simply shows the relation of parts alreadydescribed so far as they appear in such a view. K3 is thesprocket-wheel, around which the chain K plays, K3 being mounted on acam-shaft K2, Fig. l. S2 S2 are the standards supporting the cylindersand their mechanism.

In Fig. 6 is shown a plan of the parts of Fig. l, similar parts bearingthe same letters.

In Fig. 7 there is shown in dotted lines the relation of the twocylinder-spaces which are connected by a passage F. It also shows howthe circulation of water may be effected as including the cylinders fromb to d or from CZ to b, connecting-passages being made surrounding bothcylinders.

In Fig. 8 the condition of the valves during the intake stroke is shown,piston P2 lagging behind piston P, as stated, although they may, ifdesired, move in unison, the lagging arrangement of P2 being thepreferred one. The displacement of the cranks to produce this dil'erencemay be only slight, or it may be as much as forty-five degrees or evenmore. The displacement shown in the figures is about thirty degrees. InFig. 8 the inlet-valve I is shown open during the intake stroke, as alsothe fuel-supply valve G. Air is then taken into the large cylinder andair or combustible vapor or gas mingled in the small cylinder. Thiscontinues during the outward or intake stroke.

In Fig. 9 the valves are shown shut and compression is taking place bythe return of the pistons P2 P. On the completion of this stroke ringtakes place, and the condition arrived at at this time is indicated inFig. l0, the valves being closed, and the fire passes from the spaceback of piston P2 to that back of piston PQ the gases, both combustibleand air, in respective cylinders having been brought to a considerabledegree of compression. The pressure and expansion on the passage of theconnecting-rods over the dead-center give the power-stroke, on thecompletion of which the exhaust-stroke begins, and this is shown in Fig.ll, Where Pand P2 move back with the valve E alone open, causing theexhaust of both cylinders. This is followed by the taking in of a newcharge, as in Fig. S, unless the speed Voi. the machine is so risingthat the governor prevents the opening of the valves. It will be seenthat by having the pist-on P2 come near to the bottom the charge whichis drawn into the cylinder' of P2 will have very little admixture ofburned or exhaust gases, as they will have been expelled and drivenforth into the space back of P and mixed with the incoming air, which isdrawn into the cylinder of piston P.

Fig. 12 would represent au indicator-dia- IOO IlO

grain approximately such as might be obtained from the larger cylinder,the ordinates representing pressures and the abscissa or horizontalsportions of the stroke, as usual in such diagrams. 'I-Iere starting at Athe piston starting in the charge begins to be compressed, and acertainpressure is reached at B before iring. On the firing of thecharge the pressure rises to C quickly and then eX- pands until theexhaust opens at D on the curve. The diagram then is similar to thatobtained with an ordinary Otto cycle gas-engine. In the smaller cylinderthe effect is more nearly that of Fig. 13, where on the lower orascending curve compression continues from A until a certain time beforethe completion of the stroke,(assuming the cranks are displaced, say,thirty degrees) when firing takes place at a pressure indicated by B onthe ascending curve, which is the same pressure as in Fig. 12 at B. Therise of pressure continues during the further completion of thecompression stroke up to C, after which the curve returns onapproximately an adiabatic curve to B, the tendency being to form a loopbetween B and C which would represent negative power or absorbed powerduring the finish of the stroke, while the area between the curves fromB to D would represent actual power. Fig. 14 simply indicates thatduring a portion of the compression-stroke (as, e. g., during a third ofit) the cylinder of piston P may be discharging its contents through theinlet-valve, which valve is kept open for a determinate portion of thereturn stroke. Since piston P2 lags behind P in this return, very littleof the gas in P2` will be driven outward, and by arranging the passage Fon a slant, as shown, toward the center of the large cylinder scarcelyany of the combustible charge need escape, even though piston P' beallowed to pass back with the valve I open during one-half its returnstroke or compression-stroke, for during this movement piston P2 will bereaching the deadcenter and passing it, making but little difference inthe volume of gas back of it. The effect of this is to diminish theamount of compression of the compression-stroke, since the compressionbegins with the closing of the valve I. In this case, e. g., compressionmight begin in the large cylinder as in the diagram at A, Fig. 16, andbe completed at B, and explosion or burning of the charge would thenraise the pressure to C, and the fall of pressure during expansion ofthe power-strokewould carry the curve to D, which would leavea finalpressure lower than would be the case with Fig. 12 or Fig. 13. Fig. 17would indicate a similar curve for the smaller cylinder when used inthis, which may be called the partial charge cycle, for, in fact, theamount of charge taken in may be so adjusted that on the opening of theexhaust the gases have almost reached atmospheric pressure. This wouldbe done by timing the closure of the valve I, Fig. 14, in accoi-dancewith the desired amount of gas which it is proposed to compress. At thesame time since cylinder P takes in a full charge of air and maydischarge a considerable fraction thereof the tendency is to cool thecylinder and to scavenge it to a certain extent, owing to the ejectionof a portion of the cool charge admitted.

Fig. 15 indicates that in place of two cylinders, three cylinders may beconnected together, and their cranks set apart may produce similarresults-4'. e., between the pistons P? and P there maybe mounted a thirdP P with intermediate action. The charge burned in P' heats the air bothback of piston P P and PQ and the power-stroke is made by the threepistons, one after the other.

In Fig. 18 is shown a diagram representing displacement of the crankswith respect to each other through thirty degrees, the position of thecrank for the larger piston being indicated by the full line P' to thecenter, While that of the piston P2 is indicated by the full line P2 tothe center. In this position, if the arrow represent the rotation P',the crank will have passed over the center when it is just beginning theforward stroke. P2 has not reached the center, but is moving toward it.The dead-centers are assumed as upon the lines X X, or the pistons areassumed to be moved horizontally. Quite a considerable variation mayoccur in the positions of these cranks, while the system as a wholeremains nearly on the dead-point. Thus the dotted lines sho7 adisplacement backward, which carries the large piston or its crank backof the dead-point and carries the smaller crank and piston still fartherback. Should the gases, however, be iired in the smaller cylinder of theengine anywhere between the shown limits, the effectiveness of theengine in producing power is scarcely dierent for the differentpositions. Hence the ordinary action of preignition,which, if it occurin thesmaller cylinder in the position represented b v the dotted lineto center mark, would be, in a single--cylinder engine, disastrous tothe power; but since the larger piston is nearly at the point of passinga dead -center when this would occur in the double engine of myinvention, as it will have actually passed the center,when it hasstillfurther moved through a small angle, too early iiring has butlittle effect, and is immediately followed by the passage overdead-center of the large piston, which is peculiarly effective in thegeneration of power.

It will be evident that in the diagrams which have been given showingthe distribution of pressures in Figs. 12, 13, 16, and 17 a considerablevariation from the form there shown may exist in practice, whilepreserving the main features of my invention.

The engine of my invention may in part be regarded as an engine of thehot-air type with internal combustion, since the fuel charge itself whenburned does not constitute the IOO IIO

total expansible charge existing in the engine; but the burning of saidcharge with air serves to communicate heat to the large Volume of airunder pressure, thus diminishing the loss of heat to the walls of thecylinder, preventing such sudden shocks of explosion as occur inordinary engines, and securingV to a large extent immunity from hadeffects of preignition of a charge in case they occur. At the same timethere is insured the presence in the combined cylinders of a sufficientquantity of air to thoroughly complete the combustion of the fuelcharge, and in consequence of this fact it is possible to operate with acharge in the small cylinder which is richer in fuel gas or vapor, andwhich, therefore,in burning burns more slowly,at the same time that theexcess of air in the large cylinder insures the complete oxidization ofthe whole of such rich charge after explosion. On account of thedilutionof the charge by the air in thelarge cylinder there is lessliability to sudden transfers of heat to the walls, and the amount ofwater-jacketing therefore required and the loss of heat in thewaterjacket will he usually less than in the types of engine notpossessing the features of my invention.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. In an internal-combustion engine, the combination of a power cylinderand piston, a tire-cylinder and piston, both pistons having the samecycle of operation, a crank-shaft to which both of the pistons areconnected, the piston of the fire-cylinder being arranged to lag behindthat of the power-cylinder, so that on the compression the power-pistontends to force airinto the fire-cylinder, while after the ring takesplace and the powerpiston starts outward the piston in the firecylindercontinues to move inward and force the charge into the power-cylinder,differentsized clearance-spaces for the cylinders, the smaller one beingfor the fire-cylinder, and a port which connects the two cylinders andis open at all times.

2. In an internal-combustion engine, the combination of power and iirecylinders and their pistons, the piston of the fire-cylinder beingarranged to lag behind that of the power-cylinder whereby theiirst-mentioned piston will continue to move inward and force out thefuel charge after the power-piston has started on its outer stroke, acrank-disk for each piston, means for adj ustably securing the disks, aport which connects these cylinders and is always open, anadmissionvalve, an exhaust-valve, and means for actuating the valves.

3. In an internal-combustion engine, the combination of iire and powercylinders which are always in free communication, pistons for eachcylinder, that of the fire-cylinder being practically Without clearance,while that of the power-cylinder is provided with a substantial amountof clearance, a crank-shaft to which the pistons are connected, a valvefor introducing fuel into the limited space back of the lire-cylinderpiston, a valve for admitting air to the larger space back of thepower-piston, an ignition device, and an exhaust-valve which opens intothe power-cylinder.

4t. In an internal-combustion engine, the combination of fire and powercylinders which are always in open communication, pistons therefor, acrank-shaft to which the pistons are connected, an auxiliary shaftgeared to the crank-shaft, a valve for admitting fuel to thetire-cylinder, cams actuated by the auxiliary shaft for actuating thevalves, and a governor which is driven by the auxiliary shaft and isarranged to move into and out of operative engagement with the earn thatoperates the fuel-admitting valve.

5. In an internal-combustion engine, the combination of a piston, acylinder therefor, a crank-shaft, an auxiliary shaft, a fuel-admittingvalve, a cam for actuating the valve which is loosely mounted on theauxiliary shaft, a ratchet for preventing the cam from rotatingbackward, an automatic governor driven by the auxiliary shaft, and meansactuated by the governor for engaging with and driving the cam forward.

G. In an internal-combustion engine, the combination of a power-cylinderand a firecylinder which are in permanent communication through an openport, a piston for the fire-cylinder which has a slight clearance, apiston for the power-cylinder which has a much greater clearance, acrank-shaft, and means for connecting the pistons to the crankshaft insuch a manner that the piston of recylinder will lag behind that of thepowercylinder whereby all of the combustible will be discharged from thefire-cylinder.

In witness whereof I have hereunder set my hand this 13th day ofJanuary, 1898.

ELIHU THOMSON.

Witnesses:

DUGALD M. MGKILLOP, JOHN McMANUs.

IOO

